Selectively desensitized silver halide emulsion materials

ABSTRACT

WHEREIN: R1 represents an alkyl group, an unsaturated aliphatic group, or an aryl group, Z represents a heterocyclic nucleus of the thiazole series, benzothiazole series, naphthothiazole series, thiadiazole series, oxazole series, benzoxazole series, naphthoxazole series, selenazole series, benzoselenazole series, naphthoselenazole series, 2-quinoline series, pyrimidine series, quinoxaline series, quinazoline series, 1-phthalazine series, thionaphtheno (7,6-d)thiazole series, 2-pyridine series, and benzimidazole series, L represents a methine radical, Ar represents a bivalent aromatic radical, N REPRESENTS 1 OR 2, X represents an anion, but is not present when R1 itself contains an anionic group, and EACH OF R2 and R3 represents alkyl, aryl, or R2 and R3 together represent the atoms necessary to close a heterocyclic nucleus is described.   A photographic material containing a silver halide emulsion layer for recording information in the form of very short wavelength invisible electromagnetic radiation known as X-ray, wherein the sensitivity of said layer for ultra violet light and visible light is strongly reduced without substantially affecting the X-ray sensitivity of said material by incorporating therein an appropriate amount of a selective densitizing compound according to the following general formula

United States Patent [72] Inventors Robrecht Julius Thiers Brasscliaat;Theoflel Hubert Ghys, Kontich; Henri Depoorter, Mortsel, all of Belgium[21 Appl. No. 642,355

[22] Filed May 31, 1967 [45] Patented Dec. 28, 1971 [7 3 AssigneeGevaert-AGFA N.V.

Mortsel, Belgium [32] Priority July 1, 1966 [33] Great Britain [S4]SELECTIVELY DESENSITIZED SILVER HALIDE Mees, Theory of PhotographicProcess, 2nd edition, 1954, The MacMillan Co., pages 421- 422 PrimaryExaminer-Norman G. Torchin Assistant Examiner-Richard E. FichterAtt0rneys Robert F. Conrad and Alfred W. Breiner sitizing compoundaccording to the following general formula wherein:

R, represents an alkyl group, an unsaturated aliphatic group, or an arylgroup,

Z represents a heterocyclic nucleus of the thiazole series,benzothiazole series, naphthothiazole series, thiadiazole series,oxazole series, benzoxazole series, naphthoxazole series, selenazoleseries, benzoselenazole series, naphthoselenazole series, 2-quinolineseries, pyrimidine series, quinoxaline series, quinazoline series,l-phthalazine series, thionaphtheno [7,6-d]thiazole series, 2-pyridineseries, and benzimidazole series,

L represents a methine radical,

Ar represents a bivalent aromatic radical,

n represents 1 or 2,

X represents an anion, but isnot present when R, itself contains ananionic group, and

each of R, and R, represents alkyl, aryl, or R, and R together representthe atoms necessary to close a heterocyclic nucleus is described.

SELECTIV ELY DESENSITIZED SILVER HALIDE EMULSION MATERIALS Thisinvention relates to photographic elements for use in the recording ofhigh-energy short wavelength electromagnetic radiation.

It is more particularly an object of the present invention to provide aphotographic silver halide material the sensitivity of which forultraviolet and visible light is very strongly reduced withoutsubstantial loss of X-ray sensitivity.

This object has been accomplished by providing a photographic materialcontaining a silver halide emulsion layer for recording information inthe form of very short wavelength invisible electromagnetic radiationknown as X-ray, wherein the sensitivity of said layer for ultravioletlight and visible light is strongly reduced without substantiallyaffecting the X-ray sensitivity of said material by incorporatingtherein an appropriate amount of a selective densitizing compoundaccording to the following general formula:

wherein:

R, represents a substituent known in cyanine chemistry on thequaternated nitrogen atom of a heterocyclic nucleus, e. g. an alkylradical including substituted alkyl of the type generally known incyanine'dye chemistry, such as C -C alkyl including alkyl in substitutedform, e.g. methyl, ethyl, n-propyl, n-butyl, n-amyl, isopropyl,isobutyl, B- hydroxethyl, B-acetoxyethyl, sulphoethyl, sulphopropyl,sulphobutyl, sulfatopropyl, sulfatobutyl, or a substituted alkyl groupsuch as the group ACO-OB--SO OH wherein A and B each represents ahydrocarbon group as described in the UK. Pat. Specification No. 886,271filed June 20, 1957 by Gevaert Photo-Producten N,V., or the group--A-WNHVB, wherein A represents a methylene radical, an ethyleneradical, a propylene radical or a butylene radical, B represents analkyl group, an amino group, a substituted amino group and also ahydrogen atom in the case V is a single bond, and W and V eachrepresents a -CO-- radical, a -SO radical or a single bond, but at leastone of them is a SO radical as described in the U.K. Pat. SpecificationNo. 904,332 filed July 5, 1957 by Gevaert Photo-Producten N.V., anunsaturated aliphatic radical, e.g. ally], aralkyl including substitutedaralkyl e.g. benzyl and carboxybenzyl, aryl including substituted aryl,e.g. phenyl and carboxyphenyl, a cycloalkyl radical such as cyclohexyland cyclopentyl;

Z represents the necessary atoms to complete a heterocyclic nucleus ofthe type used in the production of cyanine dyes, e.g. a nucleus of thethiazole series (e.g. thiazole, 4- methylthiazole,4-methyl-5-carbethoxythiazole, 4-phenylthiazole, S-methylthiazole,S-phenylthiazole, 4-(mtolyl)-thiazle, 4-(p-bromophenyl)-thiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)- thiazole,4(m-nitrophenyl)-thiazole, a nucleus of the benzoithiazole series (e.g.benzothiazole, 4- chlorobenzothiazole, S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole,-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 6-sulphobenzothiazole, 4- phenybenzothiazole,S-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole,6-methoxybenzothiazole, S-iodobenzothiazole, 6- iodobenzothiazole,4-ethoxybenzothiazole, S-ethoxybenzothiazole,4,5,6,7-tetrahydrobenzothiazole, 5,6- dimethoxybenzothiazole,5,6-dioxymethylenebenzothiazole, S-hydroxybenzothiazole,6-hydroxybenzothiazole, 5,6-dimethylbenzothiazole), a nucleus of thenaphthotliiazole series (e.g. naphtho [2,ld] thiazole, naphtho[l,2-dl-thiazole, S-methoxynaphtho 1 ,2-d]-thiazole, 5-ethoxynaphtho[ l,2-d]- thiazole, 8-methoxynaphtho[2,l-d]thiazole,7-methoxynaphtho[2,l-d]-thiazole), a nucleus of thethionaphtheno[7,6-d]thiazole series (e.g.7-methoxythionaphtheno[7,6-d]thiazole), a nucleus of the thiadiazoleseries (e.g. 4-phenylthiadiazole), nucleus of the oxazole series (e.g.4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole,4-ethyloxazole, 4,5dimethyloxazole, 5-phenyloxazole), a nucleus of thebenzoxazole series (e.g. benzoxazole, 5- chlorobenzoxazole,S-methylbenzoxazole, 5-phenylbenzoxazole, G-methylbenzoxazole,5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole,6-methoxybenzoxazole, S-hydroxybenzoxazole, 6- hydroxybenzoxazole), anucleus of the naphthoxazole series (e.g. naphtho[2,l-d]oxazole,naphtho[l,2-d]oxazole), nucleus of the selenazole series (e.g.4-methylselenazole, 4-phenylselanazole), nucleus of the benzoselenazoleseries (e.g. benzoselenazole, 5- chlorobenzoselenazole,S-methoxybenzoselenazole, 5- hydroxybenzoselenazole, 4,5,6,7-tetrahydrobenzoselenazole), a nucleus of the naphthoselenazole series(e.g. naphtho[2,l-d]selenazole,

naphtho[ 1,2-dselenazole), those of the 2quinoline series (e.g.quinoline, 3-methyl-quinoline, S-methyl-quinoline, 7-methyl-quinoline,S-methyl-quinoline, fi-chloro-quinoline, 8-chloro-quinoline,-methoxy-quinoline, 6-ethoxyquinoline, 6-hydroxyquinoline,8-hydroxyquinoline, etc.), a nucleus of the pyrimidine series, a nucleusof the quinoxaline series, a nucleus of the quinazoline series, anucleus of the l-phthalazine series, a nucleus of the 2- pyridine series(e.g. pyridine, S-methylpyridine, 3- nitropyridine), a nucleus of thebenzimidazole series (e.g.

benzimidazole, 5,6-dichlorobenzimidazole, 5- chlorobenzimidazole, 5,-dibromobenzimidazole, 5- chloro-6-aminobenzimidazole, 5-chloro-6-bromobenzimidazole, S-phenylbenzimidazole, 5- fluorobenzimidazole,5,o-difiuorobenazimidazole, 5- cyanobenzimidazole, 5,tS-dicyanobenzimidazole, 5-

chloro--cyanobenzimidazole, 5-fluoro-6- cyanobenzimidazole,5-acetylbenzimidazole, 5-chloro-6- fluorobenzimidazole,S-carboxybenzimidazole, 7-carboxybenzimidazole,5-carbethoxybenzimidazole, 7-carbethoxybenzimidazole,5-sulphamylbenzimidazole, or 5- N-ethylsulphamybenzimidazole;

L represents methine including substituted methine, e.g. a

CH,'= C (alkyl)--,= C(aryl),= C(aralkyl)-, C- (COO-alkyl)-, =C--(CN),C(COalkyl)- or C(COaryl)radical;

Ar represents a bivalent aromatic radical, e.g. a phenylene radical, nrepresents a positive integer l or 2, x represents an 4 k)? 3 BIL 3,00 3Q and but X" is not present when R, itself contains an anionic group,and

Typical compounds included by the above general formula which haveproved to be very selective desensitizers for the purpose of theinvention are represented by the following structural formulae:

I cm,

CCII1.N-

H can I Ca s s CH: 0,N on,

III.

CgH5 oiN IIIILI- C2H5 CH J CH3 4: C113 CzIIa II3C sr -CII=N N VI CH;

CII:N- N I- CIII VII. 011:

1 CzHs CII:N N I- VIII. 02115 CH -N- N IX. C1H5 Call:

-CH=N N I- CzHr X, CH:

X11. run,

I /(Zll.1 N (III N G N (11mm),-

(ll 5 ll ('0 3 I /(}gll5 N tIILN N\ 01mm),- (iglls The above compoundscan be prepared according to techniques which are generally known to oneskilled in the art of cyanine dye chemistry.

The quantity of desensitizing azomethine dye relative to silver halidefor use according to the present invention has to be adapted dependingupon the particular silver halide emulsion and the particulardesensitizing compound used, the ratio of gelatin or other colloidbinder to silver halide, the ingredients used e.g. stabilizers and thethermal treatment of the emulsion before coating.

In general it has been observed that amounts of 1 to 1,000 mg. of saidazomethine dye per mole of silver halide are useful for obtaining thedesired difference in sensitivity between visible light and X-rays. Apreferred range of dye concentration lies between 1 and 100 mg. per moleof silver halide since thereby for a relatively strong reduction invisible light sensitivity the X-ray sensitivity of the emulsion is notsubstantially lowered.

By the wording without substantially affecting the X-ray sensitivity" weunderstand that the sensitivity for X-rays does not diminish below 70percent of the value it possesses without the addition of thedesensitizing dye.

The azomethine desensitizing dyes used according to the presentinvention substantially lower the fog level of the developed materialwhich is to be considered as a very interesting advantage.

Different type of silver halide, e.g. silver chloride, silver bromide,silver chlorobromide, silver chloroiodide and silver bromoiodide can beemployed, although we have found that iodide containing bromideemulsions, preferably containing at most 2.5 mole percent iodide areespecially useful for X-ray recording.

In order to decrease still further the sensitivity of the silver halideemulsions for ultraviolet light and visible radiation, an adequateamount of ultraviolet absorbing substance and dye e.g. a yellow dye maybe used. The filter dye may be incorporated in the emulsion layer,topcoat or protective layer and/or in the base or a backing layer.

The desensitizing dyes used according to the present invention can beadded to the light sensitive silver halide emulsion during differentpreparation steps of the light sensitive material. For example they canbe incorporated therein by a separate addition, e.g. from a solution ordispersion, or they can be added as a mixture with one or moreingredients used in the formation of the silver halide grains, duringthe physical or chemical ripening or during another step preceding thecoating of the emulsion. The desensitizing dyes can also be incorporatedin a water-permeable layer adjacent to the silver halide emulsion layer,but have then to come by diffusion in working contact with the lightsensitive silver halide.

For the purpose of increasing the gradation and accelerating thedevelopment, the said desensitizing compounds are preferably used incombination with water-soluble alkylene oxide trialkylsulphoniumproducts or polymers, e.g. as

described in the US. Pat. Specification Nos. 1,970,578 of C. Schollerand M. Wittwer, issued Aug. 21, 1934, 2,240,472 of D. R. Swan, issuedApr. 29, 1941, 2,423,549 of Ferdinand Schulze, issued July 8, 1947,2,441,389 of R. K. Blake, issued May 11, 1948, 2,531,832 of W. A.Stanton, issued Nov. 28,1950, 2,533,990 of R. K. Blake, issued Dec. 12,1950 and the UK. Pat. Specification Nos. 991,608 filed June 14, 1961 byKodak Ltd., 920,637 filed May 7, 1959, 945,340 filed Oct. 23, 1961,940,051 filed Nov. 1, 1961 and 1,015,023 filed Dec. 24, 1962 all byGevaert Photo-Producten N.V. For suitable development acceleratingpolymeric products of another type reference is made to our publishedDutch Pat. application Nos. 6,614,230 filed Oct. 10, 1966 and 6,614,291filed Oct. 1 l, 1966 Other compounds which sensitize the photographicemulsion by development acceleration, and which can be used togetherwith the selective desensitizing compounds applied according to thepresent invention are organic onium compounds and polyonium compounds,preferably of the ammonium or sulfonium type, e.g. quaternary tetraalkylarnmonium salts, alkyl-pyridinium salts, bis-alkylene pyridiniumsalts, alkylquinolinium salts, and trialkylsolphonium salts.

The selective desensitizing compounds can further be combined withchemical sensitizers known in the art e.g. sulfurcontaining compoundssuch as allyl isothiocyanate, allyl thiourea, or sodium thiosulfate,reducing compounds such as the tin compounds described in the BelgianPat. Specification Nos. 493,464 filed Jan. 24, 1950 and 568,687 filedJune 18, 1958 both by Gevaert Photo-Producten N.V., theiminoaminomethane sulfinic acid compounds described in the British Pat.Specification No. 798,823 filed Dec. 11, 1956 by Mullard Ltd., or noblemetal compounds such as gold, platinum, palladium, iridium, rutheniumand rhodium compounds.

The desensitizing compounds used according to the present invention canalso be used in combination with known stabilizing agents for silverhalide emulsions, e.g. mercury compounds, sulfur compounds such asI-phenyI-Z-tetramline-S- thion, the compounds described in the BelgianPat. Specification No. 571,916 and 571,917 both filed Oct. 10, 1958 byGevaert Photo-Producten N.V., either or not in combination withchemically sensitizing and stabilizing cadmium salts in the lightsensitive material as well as in the developer.

Together with the above-mentioned ingredients, derivatives oftetra-azaindenes, e.g. having the following general formula can be usedas fog-inhibiting compounds in the light sensitive material:

wherein:

each of R, and R, represents a hydrogen atom, an alkyl, an

aralkyl, or an aryl radical, and

R represents a hydrogen atom, an alkyl, a carboxy, or an alkoxy-carbonylgroup.

The selective desensitized silver halide emulsions can be applied byusual coating techniques to any type of support known in silver halidephotography e.g. paper, cellulose triacetate or polyester resin support.

The following examples illustrate the present invention without howeverlimiting it thereto.

Example 1 An ordinary coarse-grained silver bromoiodide (2 mole percentiodide) emulsion of the type normally used in radiography, which hadbeen chemically sensitized to its optimum speed was divided into twoportions. One portion was then treated with a desensitizing compound ofthe structural formula 1 above, the other portion of the emulsionremained untreated and served as a control. Each of the portions of theemulsions was then coated on an ordinary cellulose triacetate film base,and the coatings dried. The films obtained were then divided in twoidentical strips one of which was exposed to kilovolt X-rays through analuminum step wedge and the other strip was exposed through a grey-wedgeto an incandescent bulb emitting in the visible region of the spectrum,and provided with a filter to correct its emission spectrum towards thenormal spectrum of daylight. Each strip was then developed for 4 minutesin the following developer at 20 C.

p-monomethylaminophenol sulfate 4 g. anhydrous sodium uulfite 65 g.hydroquinone 10 g. anhydrous sodium carbonate 45 g. potassium bromide 5g. water 1,800 cc.

After development, the strips were fixed, washed and dried in the usualmanner.

The relative speeds (in percent of the control) of the strips exposed to80 kv. X-rays and visible light respectively were then measured at adensity of 1.00 above fog.

Example 1 is repeated but with a silver bromoiodide emulsion containing2.5 mole percent iodide and with a dye of structural formula VIII. Thesensitometric results are listed in table 2.

TABLE 2 Exposure to 80 Exposure to kv. X-rays visible light Mg. per mole01 Relative Relative silver speed speed halide Fog (percent) (percent)Structural formula of dye None 0. 08 100 100 VIII 13 0.01 92 15. 2

Example 3 The foregoing examples were repeated with a silver bromoiodideemulsion containing 0.35 mole percent iodide and with dyes as indicatedin the following table 3 wherein the results obtained are listed.

TABLE 3 Exposure to 80 Exposure to kv. X-rays visible light Mg. per moleof Relative Relative silver speed speed halide Fog (percent) (percent)None 0. 14 100 100 3 0. 03 98 21 20 0.01 91 3.8 10 0. 03 105 23 3 0. 03101 33 10 0.02 95 20 3 0. 02 112 60 10 0. 03 105 36 6 0. 02 98 13. 5 150.01 95 6. 8 3 0. 03 102 45 10 0. 03 100 32 We claim:

1. A photographic material comprising an X-ray sensitive silver halideemulsion layer, containing a desensitizing compound, which decreases thesensitivity to ultra violet radiation and visible light of the emulsionlayer to a greater extent than its sensitivity to X'rays wherein saidcompound is used in said emulsion layer in an amount of from about 1 to100 mg. per mole of silver halide such as not to decrease the X-raysensitivity of the emulsion layer below about 70 percent of its inherentvalue and retaining the desensitization of the emulsion to ultravioletand visible light and wherein said compound corresponds with the generalformula:

I Z ll:

X" represents an anion, but is not present when R, itself contains ananionic group, and

each of R and R represents alkyl aryl, or R, and R together representthe atoms necessary to close a heterocyclic nucleus.

2. A photographic material according to claim 1 wherein in the generalformula:

R, represents C ,-C alkyl,

Z represents the necessary atoms to complete a nucleus of the2-quinoline series or a nucleus of the benzothiazole series,

L represents a methine radical,

Ar represents a p-phenylene radical,

nrepresents l,

X'represents an anion, but is not present when R, itself contains ananionic group. and

each of R, and R represents alkyl.

3. A photographic material according to claim 1 wherein the silverhalide emulsion layer contains in addition to the said desensitizingcompound a water-soluble alkylene oxide condensation product asdeveloping accelerator and a mercury compound as stabilizing agent.

4. A photographic material according to claim 2 wherein the silverhalide emulsion layer contains in addition to the said desensitizingcompound a water-soluble alkylene oxide condensation product asdeveloping accelerator and a mercury compound as stabilizing agent.

2. A photographic material according to claim 1 wherein in the generalformula: R1 represents C1-C5 alkyl, Z represents the necessary atoms tocomplete a nucleus of the 2-quinoline series or a nucleus of thebenzothiazole series, L represents a methine radical, Ar represents ap-phenylene radical, nrepresents 1, X represents an anion, but is notpresent when R1 itself contains an anionic group, and each of R2 and R3represents alkyl.
 3. A photographic material according to claim 1wherein the silver halide emulsion layer contains in addition to thesaid desensitizing compound a water-soluble alkylene oxide condensationproduct as developing accelerator and a mercury compound as stabilizingagent.
 4. A photographic material according to claim 2 wherein thesilver halide emulsion layer contains in addition to the saiddesensitizing compound a water-soluble alkylene oxide condensationproduct as developing accelerator and a mercury compound as stabilizingagent.